Question: What is the greatest common factor of $27$ and $18$ ? Another way to say this is: $\operatorname{gcf}(27, 18) = {?}$
Answer: The greatest common factor is the largest number that is a factor of both $27$ and $18$ The factors of $27$ are $1$ $3$ $9$ , and $27$ The factors of $18$ are $1$ $2$ $3$ $6$ $9$ , and $18$ Thus, the greatest common factor of $27$ and $18$ is $9$. $\operatorname{gcf}(27, 18) = 9$